1. Field of the Invention
Exemplary aspects of the present disclosure generally relate to an image forming apparatus, such as a copier, a facsimile machine, a printer, or a multi-functional system including a combination thereof, and more particularly, an optical writer and an image forming apparatus including same.
2. Description of the Related Art
Related-art image forming apparatuses, such as copiers, facsimile machines, printers, or multifunction printers having at least one of copying, printing, scanning, and facsimile capabilities, typically form an image on a recording medium according to image data. Thus, for example, a charger uniformly charges a surface of an image bearing member (which may, for example, be a photoconductive drum); an optical writer projects a light beam onto the charged surface of the image bearing member to form an electrostatic latent image on the image bearing member according to the image data; a developing device supplies toner to the electrostatic latent image formed on the image bearing member to render the electrostatic latent image visible as a toner image; the toner image is directly transferred from the image bearing member onto a recording medium or is indirectly transferred from the image bearing member onto a recording medium via an intermediate transfer member; a cleaning device then cleans the surface of the image carrier after the toner image is transferred from the image carrier onto the recording medium; finally, a fixing device applies heat and pressure to the recording medium bearing the unfixed toner image to fix the unfixed toner image on the recording medium, thus forming the image on the recording medium.
The optical writer employed in such image forming apparatuses illuminates and scans the image bearing member with a light beam also known as write light based on image information. The latent image is developed with toner, thereby forming a visible image, also known as a toner image.
Generally, the optical writer includes a light source that generates the light beam and optical elements that shape and direct the light beam, such as a collimating lens, a cylindrical lens, a scan lens, a reflective mirror, and a light deflector such as a polygon scanner, enclosed in an optical housing. The light source, for example, a laser diode (LD), projects the light beam, which passes through the optical elements such as the collimating lens and the cylindrical lens to shape the light beam into a desired shape. Then, the light beam strikes a polygon mirror of the polygon scanner. Subsequently, the light beam is deflected and scanned by the polygon mirror, and passes through the scan lens, the reflective mirror, and so forth. Ultimately, the light beam illuminates the image bearing member from an opening covered with a dustproof pane of glass at the bottom of the optical housing of the optical writer. The optical elements and the polygon scanner are fixed to the optical housing, which has a rectangular shape.
Typically, the polygon mirror rotates fast, causing the optical housing to vibrate. When the optical housing vibrates, the optical elements fixed to the optical housing vibrate as well, resulting in changes in the position and angle of the optical elements and hence degradation of imaging quality.
To address this difficulty, the stiffness of the bottom of the optical housing is increased by curving an entire bottom surface of the optical housing, as disclosed in JP-2002-148553-A. More specifically, in this configuration, the bottom surface of the optical housing is curved in the shape of an arc of a circle.
Although advantageous, an opening through which the light beam is projected against the latent image bearing member is formed in the curved surface of the optical housing, and the stiffness of the curved surface of the optical housing with the opening is reduced undesirably as compared with the curved surface without the opening. As a result, the curved surface of the optical housing deforms. More specifically, buckling occurs from the opening so that vibration of the optical housing cannot be suppressed.
In view of the above, there is an unsolved need for an optical housing that can suppress vibration.